Display apparatus

ABSTRACT

Methods and devices for a display apparatus. In one aspect, a display apparatus includes a display device including a transparent layer, a display integrated circuit layer including one or more display control circuits, and a shielding layer between the transparent layer and the display integrated circuit layer, a near-infrared (NIR) light source and a visible light source, and a detector device including a detector integrated circuit layer including one or more detector control circuits, where a surface of the detector device contacts a surface of the display device, and a photodetector electrically coupled to at least one detector control circuit and including a detection region positioned to receive NIR light propagating from a front side of the display device to a back side of the display device along a path, where the shielding layer includes a filter region positioned in the path.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/405,573, entitled “Display Apparatus,” filed May 7, 2019, whichclaims the benefit under 35 U.S.C. § 119(e) of U.S. Patent ApplicationNo. 62/668,261, entitled “Simultaneous Optical Emission and DetectionDisplay,” filed May 8, 2018, which are incorporated herein by referencein their entirety.

BACKGROUND

Optical displays can include sensing components to facilitateinteractive features (e.g., touch, swipe, gestures, fingerprint readers,etc.) for users of the optical displays to interact with the opticaldisplays while viewing visual content on the optical displays.

SUMMARY

This specification describes technologies relating to display apparatusconfigured for simultaneous optical emission and detection of objects.

In general, one innovative aspect of the subject matter described inthis specification can be embodied in a display apparatus including adisplay device having a front side and a back side opposite the frontside and including a transparent layer, a display integrated circuitlayer including one or more display control circuit and a shieldinglayer located between the transparent layer and the display integratedcircuit layer, and a near-infrared (NIR) light source that is configuredto direct NIR light to the transparent layer and a visible light sourcethat is configured to direct visible light to the transparent layer. Thedisplay apparatus further includes a detector device located at the backside of the display device and including a detector integrated circuitlayer including one or more detector control circuits, where a surfaceof the detector device contacts a surface of the display device, and aphotodetector electrically coupled to at least one detector controlcircuit and including a detection region, the detection region beingpositioned to receive NIR light propagating from the front side of thedisplay device to the back side of the display device along a path, andwhere the shielding layer includes a filter region positioned in thepath. Other embodiments of this aspect include corresponding systems,apparatus, and computer programs, configured to perform the actions ofthe methods, encoded on computer storage devices.

These and other embodiments can each optionally include one or more ofthe following features. In some implementations, the photodetectorincludes germanium (Ge) or germanium-silicon (GeSi) material.

In some implementations, the NIR light source is electrically coupled toat least one display control circuit of the one or more display controlcircuits, and/or is electrically coupled to at least one detectorcontrol circuit of the one or more detector control circuits. The NIRlight source can be integrated with the display device and/or beintegrated with the detector. The one or more display control circuitsand the one or more detector control circuits can include thin-filmtransistors (TFTs), complementary metal-oxide semiconductor (CMOS)transistors, or a combination thereof.

In some implementations, the display device can include a liquid crystallayer below the transparent layer.

In some implementations, the display apparatus further includes a growth(e.g., monolithically integrated) or a bonding (e.g., mechanicalbonding) interface between the display device and the detector device.

In some implementations the visible light source includes an array ofvisible organic light-emitting diodes, visible micro-light emittingdiodes, or a combination thereof. The NIR light source can include anarray of NIR organic light-emitting diodes, MR micro-light emittingdiodes, or a combination thereof.

In general, another aspect of the subject matter described in thisspecification can be embodied in a display apparatus including a displaydevice having a front side and a back side opposite the front side andincluding a transparent layer, a shielding layer arranged between thetransparent layer and the back side of the display device, the shieldinglayer including a filter region, a NIR light source configured to directNIR light to the transparent layer, and a detector device including adetector integrated circuit layer including one or more detector controlcircuits, and a photodetector electrically coupled to at least onedetector control circuit of the one or more detector control circuits.

These and other embodiments can each optionally include one or more ofthe following features. In some implementations, the display devicefurther includes a display integrated circuit layer including one ormore display control circuits.

The detection region of the photodetector can be aligned with the filterregion in a vertical direction. In some implementations, the displaydevice further includes a visible light source electrically coupled toat least one display control circuit of the one or more display controlcircuits, where the visible light source is configured to direct visiblelight to the transparent layer. In some implementations, the NIR lightdirected by NIR light source to the transparent layer is not overlappedwith visible light directed by the visible light source to thetransparent layer within the transparent layer.

In some implementations, the display apparatus can further include abacklight module under the display device, where the display devicefurther includes a liquid crystal layer below the transparent layer. Thedetector device can be located between the display device and thebacklight module.

Particular embodiments of the subject matter described in thisspecification can be implemented so as to realize one or more of thefollowing advantages. An advantage of this technology is that thedisplay apparatus can simultaneously emit light and monitor reflectedlight from an object (e.g., a user's fingers). The detector can be usedto monitor various properties of the reflected light (e.g.,polarization, intensity, phase, etc.) and then infer the properties ofthe object through techniques such as amplitude image detection and/ordepth image detection, for example, using time-of-flight measurements.By detecting reflected wavelengths of near-infrared (NIR) light that arelonger, e.g., >1 micron, the described technology can reduceinterference at the detector caused by visible light emitted by thedisplay and from the ambient, improve device performance by shieldingthe integrated circuit layers (e.g., including thin-film transistors,i.e., TFTs on amorphous, polycrystalline, or other type of silicon) fromthe visible light, and improve bio-layer penetration and sensing bypushing to longer NIR wavelengths.

In some implementations, a display apparatus can be configured to havecontrol circuits that are TFTs, which have lower processing temperaturerelative to traditional CMOS devices, making achieving a lower thermalbudget (e.g., staying below thermal budget of Ge detector) easier.

The details of one or more embodiments of the subject matter describedin this specification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages of thesubject matter will become apparent from the description, the drawings,and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A through 1E are cross-sectional schematics of example displayapparatuses.

FIGS. 2A through 2E are cross-sectional schematics of example displayapparatuses.

FIG. 3 is a circuit diagram of an example detector device.

FIG. 4 is a circuit diagram of another example detector device.

FIGS. 5A and 5B are schematics of example display apparatuses.

FIG. 6 is an example process for a display apparatus for emitting lightand detecting the proximity of objects.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

Overview

This specification describes technologies related to a display apparatusthat can simultaneously emit light and detect the proximity of objects(e.g., a user finger, hand, or face near the display). The technologyutilizes a GeSi or Ge detector to detect near-infrared (NIR) light thatis reflected off objects that are in close proximity to the displayapparatus to determine an amplitude image and/or a depth image of theobjects relative to the display apparatus.

More particularly, the technology incorporates a display device, adetector device, a red-green-blue (RGB) light source, and anear-infrared (NIR) light source. A bottom surface of the display deviceis in contact with a top surface of the detector device by, e.g.,monolithic growth, mechanical bonding, or other similar methods.

The NIR light source is configured to emit NIR light that is arranged tobe incident substantially normal to a surface of the display device. Insome embodiments, the NIR light source is integrated with the displaydevice or the detector device. In some embodiments, the NIR light has apeak wavelength not less than 1000 nm (e.g., 1.55 microns or 1.31microns or 1.064 microns). In some embodiments, the NIR light has a peakwavelength not greater than 2000 nm. The NIR light source can be, forexample, an organic light-emitting diode (OLED), a micro light-emittingdiode (Micro-LED), an LED, a vertical cavity surface emitting laser(VCSEL), an edge emission laser (EEL) such as distributed-feedback (DFB)laser or distributed-Bragg reflector (DBR) laser, and laser diode, etc.,and is arranged in an array format every one or few pixels of thedisplay device.

The display device includes i) a transparent layer (e.g., a protectiveglass) ii) a first electrode area (e.g., transparent conductive oxidelayer, metal layer) iii) a second electrode area (e.g., transparentconductive oxide layer, metal layer) iv) display integrated circuits(IC) layer including a multiple display control circuits (e.g., CMOStransistors, TFTs, other control devices) and v) a shielding layer toprevent visible light from reaching the IC layer (e.g., to preventvisible light from the ambient, reflective visible light from thedisplay, etc. from reaching the IC layer). In some implementations, theshielding layer can include a first filter region for allowing a NIRlight having a peak wavelength no less than 1000 nm passing through. Thefirst filter region is overlapped with the detector device but notoverlapped with the NIR light source in a vertical direction. The firstfilter region may function as an optical interference filter. Theshielding layer and the NIR light source may be between the displayintegrated circuits layer and the transparent layer.

In some embodiments, the NIR light source is between the first electrodearea and the second electrode area. The NIR light source is electricallycoupled to at least one display control circuit of the multiple displaycontrol circuits via the second electrode area.

The red-green-blue (RGB) light source is configured to emit RGB lighthaving peak wavelengths different from the peak wavelength of the NIRlight emitted from the MR light source. The RGB light source (e.g.,OLED, Micro LED, LED, etc.) is arranged in an array format every one orfew pixels. The NIR light source is not overlapped with the RGB lightsource in a vertical direction, where emission of both the NIR lightsource and the RGB light source are aligned in the vertical direction.In some embodiments, the shielding layer can include a second filterregion for allowing the NIR light source having a peak wavelength noless than 1000 nm passing through (e.g., 1.064 microns, 1.31 microns,1.55 microns, or the like). The first filter region is separated fromthe second filter region from a cross sectional of view of the displayapparatus.

The detector device includes i) a detecting integrated circuit (IC)layer including multiple detector control circuits (e.g., complementarymetal-oxide semiconductor (CMOS) transistors, thin-film transistors(TFTs), or other control devices) and ii) a detector (e.g., a SiGedetector, Ge-on-Si detector, etc.), where the detector is locateddirectly underneath the first filter region. The detector is inelectrical contact with at least one detector control circuit from thedetecting IC layer.

In some embodiments, the detector device performs time-of-flightmeasurements of the reflected NIR light originating from the NIR lightsource(s). In some embodiments, the detecting IC layer is supported by acarrier substrate. The detector is supported by a donor substrate. Abonding layer exists in between the detector and the detecting IC layerfor establishing electrical connection.

In some embodiments, the display apparatus includes a liquid crystaldisplay (LCD). The display device can include a liquid crystal layerbetween a first electrode area and a second electrode area. The displayapparatus can further include a backlight module positioned under thedisplay device, and a first and a second polarizer film sandwiching theliquid crystal layer. A color filter can be located between the firstpolarizer and the second polarizer. A detector device can be locatedbetween the backlight module and the display device.

Example Display Apparatus

FIG. 1A is a cross-sectional schematic of an example display apparatus100. Display apparatus 100 includes a display device 102 and a detectordevice 104. Display device 102 and detector device 104 can be alignedusing, for example, wafer/die bonding, chip stacking, or another similarmethod, where a first surface 103 of the display device 102 is incontact with a second surface 105 of the detector device 104.

Display device 102 includes a transparent layer 106, a displayintegrated circuit layer 108, a shielding layer 110, and a firstelectrode area (e.g., a transparent conductive oxide layer) 112.Additionally, the display device 102 includes a light source 114, wherethe light source 114 is in electrical and physical contact with at leastone display control circuit 116 in the display integrated circuit layer108.

Transparent layer 106 is a packaging layer, e.g., a glass layer, plasticlayer, or composite layer, with transparency above at least 50% over abroadband spectrum, e.g., visible and near-infrared wavelengths. In oneexample, the transparent layer 106 has a 90% transmission rate for abroadband spectrum ranging from 380 nm to 1.55 microns. Transparentlayer 106 can act as a physical barrier to protect the other layers ofthe display device 102 from ambient conditions (e.g., waterproof, UVprotection, shatter-resistance, scratch-resistant, etc.).

The display integrated circuit layer 108 is an amorphous silicon (a-Si),a polycrystalline silicon (p-Si), or other types of silicon layers andinclude multiple display control circuits 116. The display controlcircuits 116 can include, for example, a thin-film transistor (TFT)device, where the multiple display control circuits 116 can befabricated in a multi-layer structure within the silicon layer of thedisplay integrated circuit layer 108. The TFT devices can be, forexample, staggered or coplanar construction, and can be fabricated usingCMOS fabrication techniques. Fabrication details of the displayintegrated circuit layer 108 are discussed in further detail below.

In some implementations, the display device 102 further includes asecond electrode area 109, e.g., a second transparent conductive oxidelayer or metal/metallic layer, in the display integrated circuit layer108. The second electrode area 109 is in electrical and physical contactwith the light source 114, where the NIR light source 114 is locatedbetween and in electrical contact with the first electrode area 112 andthe second electrode area 109.

In some implementations, the display integrated circuit layer 108 is apart of an active-matrix organic light-emitting diode (AMOLED) displayscreen where the display integrated circuit layer 108 includes a displaycontrol circuit 116 (e.g., a circuit including TFT devices) for eachpixel on the AMOLED display screen.

In some implementations, the display integrated circuit layer 108 is apart of a thin-film transistor liquid crystal display (TFT LCD), whereeach of the multiple display control circuits 116 are embedded withinthe TFT LCD panel. LCD type display apparatuses are discussed in furtherdetail below, with reference to FIGS. 5A and 5B.

Shielding layer 110 is located between the display integrated circuitlayer 108 and the first electrode area 112. Shielding layer 110 iscomposed in part of a filtering material, e.g., a polymer or othermaterial absorbing visible wavelengths to prevent visible wavelengthsfrom reaching particular layers of the display device 102 and detectordevice 104, e.g., the display integrated circuit layer 108 and thelayers of the detector device 104. The shielding layer 110 can becomposed in part of polymer materials such as colored polyethylene orpolypropylene or the like.

The shielding layer 110 includes a first filter region 118. The firstfilter region 118 is overlapped with a detector 122 of the detectordevice 104 but not overlapped with the light source 114 in a verticaldirection substantially normal to a front surface 123 of the displaydevice 102. The first filter region 118 of the shielding layer 110 canbe configured to be an optical filter that reflects one or more spectralbands or lines and transmits others, while maintaining a nearly zerocoefficient of absorption for all wavelengths of interest, e.g., thenear-infrared wavelength spectrum. The optical filter of the firstfilter region 118 can be, for example, an interference filter (e.g., ahigh-pass filter, a low-pass filter, a band-pass filter, aband-rejection filter, or a dichroic filter). The first filter region118 is configured to allow near-infrared light, e.g., NIR light 125reflected from an object 121, to penetrate through the front surface 123of the display device 102 and reach the detector 122 of the detectordevice 104. The first filter region 118 can include, for example,different dielectric material with different refractive index. The firstfilter region 118 can be an area of the shielding layer 110 in adirection perpendicular to the front surface 123 that ranges between afew microns to hundreds of microns, and that is at least a thresholdarea to allow for reflected NIR light 125 from the light source 114 toreach the detector 122.

The first electrode area 112 is located between the transparent layer106 and the shielding layer 110. The first electrode area 112 includesone or more thin films of optically transparent (e.g., in the visibleand near-infrared spectrums) and electrically conductive material. Thefirst electrode area 112 can include transparent conductive oxidematerial (for example, indium tin oxide (ITO)), conductive polymers,metal or metallic grids or networks, carbon nanotubes, or other similarmaterials.

Light source 114 is electrical coupled to at least one display controlcircuit 116 of the multiple display control circuits of the displayintegrated circuit layer 108. In some implementations, the light source114 is located between the first electrode area 112 and the secondelectrode area 109, and is electrically coupled to at least one displaycontrol circuit 116 of the multiple display control circuits via thesecond electrode area 109.

Though depicted in FIG. 1A as one light source 114, light source 114 isone of multiple light sources 114, where the multiple light sources 114are included in an array of light sources. In some implementations, thearray of light sources consists of sub-array units, where each sub-arrayunit includes multiple light sources 114, for example, an red-green-blue(RGB) light source (e.g., a red light source, a blue light source, agreen light source, or a light source capable of emitting red, green andblue light simultaneously), and a near-infrared (NIR) light source. TheRGB light source is configured to emit RGB light having peak wavelengthsdifferent from the peak wavelength of the NIR light emitted from the NIRlight source. The RGB light source (e.g., an organic light-emittingdiode (OLED), Micro light emitting diode (LED), LED, etc.) is arrangedin an array format every one or few pixels.

The NIR light source is not overlapped with the RGB light source in avertical direction, where emissions of both the NIR light source and theRGB light source are aligned in the vertical direction. The NIR lightsource 114 is a light source, for example, an organic light-emittingdiode (OLED), Micro light emitting diode (LED), LED, a vertical cavitysurface emitting laser (VCSEL), an edge emission laser (EEL) such asdistributed-feedback (DFB) laser or distributed-Bragg (DBR) laser, andlaser diode etc., that emit a range of wavelengths between, ˜700 nm to˜1.65 microns.

Light source 114 can be fabricated with the display device 102, forexample, during the fabrication process of forming the displayintegrated circuit layer 108. Other methods for configuring the lightsource 114 with respect to the display device 102 and/or the detectordevice 104 are discussed below with reference to FIGS. 1B through 1E.

The detector device 104 includes one or more detectors 122 and adetector integrated circuit layer 126, supported by a substrate 127(e.g., a silicon substrate). The detector integrated circuit layer 126includes multiple detector control circuits 128, where each detector 122of the one or more detectors 122 is in electrical contact, e.g., viainterconnect 129, with at least one of the multiple detector controlcircuits 128. The multiple detector control circuits 128 can be, forexample, a complementary metal-oxide semiconductor (CMOS) device, a TFTdevice, or a combination thereof. The multiple detector control circuits128 can be arranged in a multi-layer (e.g., two or more interconnectedlayers) array within the detector integrated circuit layer 126.

A type of detector control circuit 128 utilized for a particulardetector integrated circuit layer 126 can be selected in part based on amaterial of the detector integrated circuit layer 126. In one example, amaterial of the detector integrated circuit layer 126 is crystallinesilicon and the detector control circuit 128 is a CMOS device-basedcircuit. In another example, the material of the detector integratedcircuit layer 126 is a-Si/p-Si/other types of silicon and the detectorcontrol circuit 128 is a TFT device-based circuit. Further discussion ofa detector integrated circuit layer 126 including a-Si/p-Si/other typesof silicon is discussed below with reference to FIGS. 2A through 2E.

Each detector 122 of the one or more detectors 122 is electricallyconnected to at least one detector control circuit 128 which can beconfigured to operate the detector 122, e.g., to apply a bias to thedetector 122, receive electrical signal that is a measure of an opticalsignal absorbed within the detector 122, etc. The detectors 122 can bearranged in an array, where each of the detectors 122 of the array ofmultiple detectors, is aligned within the first filter region 118 of thedisplay device 102 when the display device 102 and the detector device104 are aligned and bonded together at the respective first surface 103and second surface 105.

Detector 122 can be, for example, a germanium (Ge) detector, or asilicon-germanium (SiGe) detector. In general, the detector 122 can havea detection region having a range thicknesses of 0.5 micron to 5microns, where a thickness of the detection region of the detector 122is selected in part to facilitate the absorption of reflected NIR light125 within the detection region of the detector 122. The detector 122converts the absorbed reflected NIR light 125 into electrical signal,which can be collected by the one or more electrically connecteddetector control circuits 128 of the detector integrated circuit layer126. In some implementations, a detector 122 can be a photodetector,e.g., a single-output photodetector or a dual-output photodetector forperforming time-of-flight measurements, which is discussed in furtherdetail with reference to FIGS. 3 and 4.

In some implementations, the detector 122 and the detector integratedcircuit layer 126 are each fabricated on respective substrates, e.g.,crystalline silicon substrates. Each of the respective substrates can beprocessed using, for example, wafer-grinding and wafer polishing, toremove a portion or all of the respective substrates. The processedsubstrates can be bonded together such that the reflected NIR light 125enters the detector 122 through the detector integrated circuit layer126. The substrates can be bonded together using an interconnect circuit(IC) layer 130, including multiple interconnects 129, where the multipleinterconnects 129 of the IC layer 130 electrically connect detectors 122to detector control circuits 128. In some implementations, the detectorand the detector integrated layer 126 are fabricated on the samesubstrates, e.g., crystalline silicon substrates.

When display device 102 and detector device 104 are aligned and bondedsuch that the first surface 103 and the second surface 105 of therespective devices are in contact, the detection region of the detector122 is positioned to receive the reflected NIR light 125 propagatingfrom the front side of the display device 102 to the back side of thedisplay device 102, in which the first filter region 118 of theshielding layer 110 is positioned in-between the MR path. In otherwords, a location of the detector 122 is such that reflected NIR light125 entering the transparent layer 106 can pass through the area definedby the first filter region 118 and be absorbed in the detection regionof the detector 122.

In some implementations, the detector integrated circuit layer 126 isbetween the detector 122 and the display device 102 such that thereflected NIR light 125 enters the detector 122 through the detectorintegrated circuit layer 126. In some implementations, the detector 122is between the detector integrated circuit layer 126 and the displaydevice 102 such that the reflected NIR light 125 enters the detector 122without passing through the detector integrated circuit layer 126.Materials of the intervening layers traveled by the reflected NIR light125 between the transparent layer 106 and the detector 122 can beselected in part to reduce an amount of attenuation of the reflected NIRlight 125 within the display apparatus 100. In some implementations, thematerials of the intervening layers are selected such that an amount ofattenuation of the reflected NIR light 125 is below a thresholdattenuation amount.

In some implementations, one or more dimensions of the first filterregion 118 can be selected to maximize an amount of reflected NIR light125 reaching the detector 122 when the display device 102 and detectordevice 104 are aligned and bonded together. An amount of reflected NIRlight 125 reaching the detector 122 can depend in part on an acceptanceangle for the detector 122, in other words, the angle of incidentreflected NIR light 125 on the front surface 123 of the transparentlayer 106 that have line-of-sight of the detector 122 via the firstfilter region 118. A minimum range of acceptance angles can determine,for example, relative thicknesses of each intervening layer (e.g., ofthe shielding layer 110, display integrated circuit layer 108, anddetector integrated layer 126).

In some implementations, reflected NIR light 125 is NIR light emitted bylight source 114 that reflects off of an object 121 and is absorbed by adetection region of detector 122. Object 121 can be, for example, afinger, hand, or face. Reflected NIR light 125 from an object 121located a distance 132 from front surface 123 can be collected based inpart on a type of the object 121. For example, reflected NIR light 125can be collected from an object 121 that is a finger at a distance 132that is a few millimeters away (e.g., between 1 mm and 5 mm). In anotherexample, reflected NIR light 125 can be collected from an object 121that is a hand at a distance 132 that is a few to tens of centimetersaway (e.g., between 2 cm and 50 cm, 15 cm, 30 cm, etc.). In anotherexample, reflected NIR light 125 can be collected from an object 121that is a face at a distance 132 that is tens to hundreds of centimetersaway (e.g., between 10 cm and 200 cm, 80 cm, 150 cm, etc.).

Additional details of the operation of the display apparatus 100 isdescribed below with reference to FIG. 6.

FIG. 1A depicts a display apparatus 100, according to some embodiments.FIGS. 1B through 1E depict the display apparatus 100, according to otherembodiments.

Other Embodiments of the Display Apparatus

Though depicted in FIG. 1A as a display device 102 and a detector device104 that are bonded together at first surface 103 and second surface105, other configurations for the display apparatus 100 are possible.FIG. 1B is a cross-sectional schematic of another example displayapparatus 140. The display apparatus 140 depicted in FIG. 1B is amonolithically integrated structure, that is, that the display device102 and detector device 104 are fabricated using monolithic fabricationtechniques, e.g., epitaxial and/or lateral growth techniques, that doesnot involve a mechanical bonding step to unify the display device 102and the detector device 104 at the interface 142.

In some implementations, thermal budget constraints can determinefabrication processes available for fabricating the monolithicallyintegrated structure of display apparatus 140. For example, detector 122can be a Ge detector and has a thermal budget of 800° C., where anystructures of the display apparatus 140 that are fabricated after the Gedetector 122 are restricted to not exceed 800° C.

In some implementations, the display apparatus 140 can be fabricatedutilizing both a mechanical bonding technique and a monolithicintegrated technique. For example, the display device 102 and thedetector device 104 may each be monolithically integrated and thenmechanically bonded together at interface 142, e.g., where the detectordevice 104 does not consist of two substrates bonded together with an IClayer 130 but is fabricated as a single device monolithically.

In some implementations, the detector integrated circuit layer 126 isbetween the detector 122 and the display device 102 such that thereflected NIR light 125 enters the detector 122 through the detectorintegrated circuit layer 126. In some implementations, the detector 122is between the detector integrated circuit layer 126 and the displaydevice 102 such that the reflected NIR light 125 enters the detector 122without passing through the detector integrated circuit layer 126.

FIG. 1C is a cross-sectional schematic of another example displayapparatus 150. Display apparatus 150 includes light sources 154 (e.g.,RGB light sources 114) that are integrated into display device 102,where light sources 154 include an array of light sources 154 emittingvisible light 156. In contrast to display apparatus 100 depicted in FIG.1A, display apparatus 150 in FIG. 1C includes a light source 160 that isseparated from the display device 102 and the detector device 104 andwhich is packaged beneath the display device 102 in contact with thefirst surface 103 of the display device 102. The light source 160 is aNIR light source, for example, a packaged laser diode, vertically-cavitysurface emitting laser (VCSEL), an edge emission laser (EEL) such asdistributed-feedback (DFB) laser or distributed-Bragg reflector (DBR)laser, an organic light-emitting diode (OLED), Micro light emittingdiode (LED), LED or the like, that is separately fabricated, diced, andbonded or otherwise attached to a back side of the display device 102 incontact with the first surface 103. In one example, the light source 160can be an InGaAs/InP VCSEL.

Light source 160 is positioned and bonded at the back side of thedisplay device 102 such that the light source 160 emits NIR light 164perpendicular to the front surface 123 of the transparent layer 106 ofthe display device 102. Display device 102 additionally can include asecond filter region 166 which includes a same composition as firstfilter region 118. The second filter region 166 is embedded in theshielding layer 110 and aligned within the light source 160 such thatthe NIR light 164 emitted by the light source 160 passes through thesecond filter region 166 when the light source 160 is positioned andbonded at the back side of the display device 102.

In some implementations, the light source 160 is in electrical contactwith IC layer 130 via one or more interconnects 129, where light source160 can be connected to one or more laser control devices 168 via the IClayer 130. The multiple laser control devices 168 can be, for example,TFT devices, CMOS devices, or a combination thereof, and can providecontrol instructions, power, etc., to the light source 160 to operatethe light source 160. Laser control devices 168 can be arranged in amulti-layer array within the detector integrated circuit layer 126,where each laser control device 168 can be in electrical contact with arespective light source 160. In some implementations, the multiple lasercontrol devices 168 can be fabricated on a substrate different from thesubstrate 127, and electrically connect to the light source 160 tooperate the light source 160.

In some implementations, the detector integrated circuit layer 126 isbetween the detector 122 and the display device 102 such that thereflected NIR light 125 enters the detector 122 through the detectorintegrated circuit layer 126. In some implementations, the detector 122is between the detector integrated circuit layer 126 and the displaydevice 102 such that the reflected NIR light 125 enters the detector 122without passing through the detector integrated circuit layer 126.

Though depicted in FIG. 1C as one light source 160, multiple lightsources 160 can be included in the display apparatus 150, where thelight sources 160 are distributed in an array having a spacing of one orfew pixels. In some implementations, the light sources 160 can bescanning lasers, where an emitted NIR light 164 can be scanned in an arcor another scanning pattern through a range of angles.

FIG. 1D is a cross-sectional schematic of another example displayapparatus 170. Similar to the display apparatus 160 depicted in FIG. 1C,display apparatus 170 includes a detector device 104 where the NIR lightsource 172 (e.g., light source 160 depicted in FIG. 1C) is separatedfrom the RGB light source 154. Distinctly, display apparatus 170 of FIG.1D includes a NIR light source 172 that is integrated into the detectordevice 104. The NIR light source 172 can be fabricated on the detectordevice 104, e.g., using epitaxial and/or lateral growth methods.Alternatively, the NIR light source 172 can be fabricated and dicedseparately, and then integrated as a die to the detector device 104 bybonding the die to the substrate 127 of the detector device 104 via theIC layer 130. In some implementations, the detector integrated circuitlayer 126 is between the detector 122 and the display device 102 suchthat the reflected NIR light 125 enters the detector 122 through thedetector integrated circuit layer 126. The MR light source 172 and thedetector 122 are respectively at two opposite sides of the IC layer 130.In some implementations, the detector 122 is between the detectorintegrated circuit layer 126 and the display device 102 such that thereflected NIR light 125 enters the detector 122 without passing throughthe detector integrated circuit layer 126. The NIR light source 172 andthe detector 122 are at the same side of the IC layer 130. The NIR lightsource 172 may be embedded in the substrate 127 at a position directlyunder the second filter region 166.

Subsequent to integrating the NIR light source 172 in the detectordevice 104, the detector device 104 and the display device 102 arebonded together, e.g., using wafer/die bonding techniques, at the firstsurface 103 and the second surface 105, as described above withreference to FIG. 1A.

FIG. 1E is a cross-sectional schematic of another example displayapparatus 180. The display apparatus 180 depicted in FIG. 1E is amonolithically integrated structure of the display apparatus 170described above with reference to FIG. 1D. Monolithic integration of thedisplay apparatus 180 includes a display device 102 and a detectordevice 104 that are fabricated using monolithic fabrication techniques,e.g., epitaxial and/or lateral growth techniques, that does not involvea mechanical bonding step to unify the display device 102 and thedetector device 104 at the interface 182.

In some implementations, the NIR light source 172 can protrude into thedisplay integrated control layer 108 (e.g., the a-Si layer) of thedisplay device 102, where growth of the a-Si layer for the displayintegrated control layer 108 using monolithic integration techniques canbe, in part, a lateral growth of a-Si over the NIR light source 172.

In some implementations, the NIR light source 172 can be beneath thea-Si layer of the display device, where the NIR light source 172 isembedded within the detector device 104 and below the interface 182,such that the NIR light source 172 is not located within the displaydevice 102.

In some implementations, thermal budget constraints can determinefabrication processes available for fabricating the monolithicallyintegrated structure of display apparatus 180. For example, detector 122can be a Ge detector and has a thermal budget of 800° C., where anystructures of the display apparatus 140 that are fabricated after the Gedetector 122 are restricted to not exceed 800° C. In another example,NIR light source 172 can be an InGaAs/InP VCSEL and has a thermal budgetnot exceeding 600° C. after the NIR light source 172 is epitaxiallyand/or laterally grown on the IC layer 130 of the detector device 104.

In some implementations, the display apparatus 180 can be fabricatedutilizing both a mechanical bonding technique and a monolithicintegrated technique. For example, the display device 102 and thedetector device 104 may each be monolithically integrated and thenmechanically bonded together at interface 182, e.g., where the detectordevice 104 does not consist of two substrates bonded together with an IClayer 130 but is fabricated as a single device monolithically. Inanother example, the detector device 104 can include a bonding step tointegrate the NIR light source 172 with the detector device 104, e.g.,to bond the MR light source 172 with the IC layer 130, and where otheraspects of the display apparatus (e.g., the detector integrated circuitlayer 126 and the display device 102) are fabricated using monolithicintegrated techniques. In some implementations, the detector integratedcircuit layer 126 is between the detector 122 and the display device 102such that the reflected NIR light 125 enters the detector 122 throughthe detector integrated circuit layer 126. The MR light source 172 andthe detector 122 are respectively at two opposite sides of the IC layer130. In some implementations, the detector 122 is between the detectorintegrated circuit layer 126 and the display device 102 such that thereflected NIR light 125 enters the detector 122 without passing throughthe detector integrated circuit layer 126. The NIR light source 172 andthe detector 122 are at the same side of the IC layer 130. In someimplementations, the NIR light source 172 may be embedded in thesubstrate 127 at a position directly under the second filter region 166.

In some embodiments, the detector device 102 depicted in FIGS. 1Athrough 1E includes a detector integrated layer 126 including amorphoussilicon (a-Si), polycrystalline silicon (p-Si), or other types ofsilicon rather than crystalline silicon, where the detector controlcircuits 128 are TFT devices rather than CMOS devices. FIGS. 2A through2E depict these embodiments of display apparatuses which include adetector integrated layer including a-Si/p-Si/other types of silicon andcorresponding detector control circuits that are TFT devices.

FIG. 2A is a cross-sectional schematic of another example displayapparatus 200. Display apparatus 200 includes a display device 202(e.g., display device 102 as describe with reference to FIG. 1A) and adetector device 204. As noted above, detector device 204 is distinctfrom detector device 104 described above with reference to FIG. 1A inthat the detector integrated layer 226 of the detector device 204includes amorphous silicon, polycrystalline silicon, or other types ofsilicon that are not crystalline silicon, and the multiple detectorcontrol devices 228 are TFT devices.

In some implementations, detector 222 of the detector device 204 issupported by the substrate 227 (e.g., a crystalline silicon substrate)and the subsequently, the detector integrated layer 226 is fabricated ona surface 231 of the substrate 227 including one or more a-Si/p-Si/othertypes of silicon layers and multiple detector control circuits 228. Insome implementations, the detector integrated circuit layer 226 isbetween the detector 222 and the display device 202 such that thereflected NIR light 125 enters the detector 222 through the detectorintegrated circuit layer 226. In some implementations, the detector 222is between the detector integrated circuit layer 226 and the displaydevice 202 such that the reflected NIR light 125 enters the detector 222without passing through the detector integrated circuit layer 226.

As depicted in FIG. 2A, the detector device 204 does not include thesame IC layer 130 that is described for the display apparatus 100 ofFIG. 1A. As such, interconnects 229 are used to electrically connect thedetector control circuits 228 and respective detectors 222.

FIG. 2B is a cross-sectional schematic of another example displayapparatus 240. The display apparatus 240 depicted in FIG. 2B is amonolithically integrated structure, that is, that the display device202 and detector device 204 are fabricated using monolithic fabricationtechniques, e.g., epitaxial and/or lateral growth techniques, that doesnot involve a mechanical bonding step to unify the display device 202and the detector device 204 at the interface 242. The detectorintegrated circuit layer 226 and display integrated circuit layer 208both include a-Si/p-Si/other types of silicon material. Thus, afabrication technique, e.g., epitaxial and/or lateral growth, can beused to epitaxially integrate the detector integrated circuit layer 226and display integrated circuit layer 208 across the interface 242between the two layers.

In some implementations, thermal budget constraints can determinefabrication processes available for fabricating the monolithicallyintegrated structure of display apparatus 240. For example, detector 222can be a Ge detector and has a thermal budget of 800° C., where anystructures of the display apparatus 240 that are fabricated after the Gedetector 222 are restricted to not exceed 800° C.

In some implementations, the display apparatus 240 can be fabricatedutilizing both a mechanical bonding technique and a monolithicintegrated technique. For example, the display device 202 and thedetector device 204 may each be monolithically integrated and thenmechanically bonded together at interface 242 and where the detectordevice 204 is fabricated as a single device monolithically. In someimplementations, the detector integrated circuit layer 226 is betweenthe detector 222 and the display device 202 such that the reflected NIRlight 125 enters the detector 222 through the detector integratedcircuit layer 226. In some implementations, the detector 222 is betweenthe detector integrated circuit layer 226 and the display device 202such that the reflected NIR light 125 enters the detector 222 withoutpassing through the detector integrated circuit layer 226.

FIG. 2C is a cross-sectional schematic of another example displayapparatus 250. Display apparatus 250 includes light sources 254 (e.g.,RGB light sources 214) that are integrated into display device 202,where light sources 254 include an array of light sources 254 emittingvisible light 256. In contrast to display apparatus 200 depicted in FIG.2A, display apparatus 250 in FIG. 2C includes a light source 260 that isseparately fabricated from the display device 202 and detector device204 and which is packaged beneath the display device 202 in contact witha surface 262 of the display device 202. Light source 260 is a NIR lightsource, for example, a packaged laser diode, vertically-cavity surfaceemitting laser (VCSEL), an edge emission laser (EEL) such asdistributed-feedback (DFB) laser or distributed-Bragg reflector (DBR)laser, an organic light-emitting diode (OLED), Micro light emittingdiode (LED), LED or the like, that is separately fabricated, diced, andbonded or otherwise attached to a back side of the display device 202 incontact with surface 262. In one example, the light source 260 can be anInGaAs/InP VCSEL.

Light source 260 is positioned and bonded at the back side of thedisplay device 202 such that the light source 260 emits NIR light 264perpendicular to surface 223 of the transparent layer 206 of the displaydevice 202. Display device 202 additionally can include a second filterregion 266 which includes a same composition as first filter region 218(e.g., first filter region 118 of FIG. 1A). The second filter region 266is embedded in the shielding layer 210 (e.g., shielding layer 110 ofFIG. 1A) and aligned within the shielding layer 210 such that the NIRlight 264 emitted by the light source 260 passes through the secondfilter region 266 when light source 260 is positioned and bonded at theback side of the display device 202. In some implementations, thedetector integrated circuit layer 226 is between the detector 222 andthe display device 202 such that the reflected NIR light 125 enters thedetector 222 through the detector integrated circuit layer 226. In someimplementations, the detector 222 is between the detector integratedcircuit layer 226 and the display device 202 such that the reflected NIRlight 125 enters the detector 222 without passing through the detectorintegrated circuit layer 226.

Light source 260 is in electrical contact with one or more interconnects229, where light source 260 can be connected to one or more lasercontrol devices 268 via the interconnects 229. The multiple lasercontrol devices 268 can be, for example, TFTs, CMOS devices, or acombination thereof, and can provide control instructions, power, etc.,to the light source 260 to operate the light source 260. Laser controldevices 268 can be arranged in a multi-layer array within the detectorintegrated circuit layer 226, where each laser control device 268 can bein electrical contact with a respective light source 260. In someimplementations, the multiple laser control devices 268 can befabricated on a substrate different from the substrate 227, andelectrically connect to the light source 260 to operate the light source260.

Though depicted in FIG. 2C as one light source 260, multiple lightsources 260 can be included in the display apparatus 250, where thelight sources 260 are distributed in an array having a spacing of one orfew pixels. In some implementations, the light sources 260 can bescanning lasers, where an emitted NIR light 164 can be scanned in an arcor another scanning pattern through a range of angles.

FIG. 2D is a cross-sectional schematic of another example displayapparatus 270. Similar to the display apparatus 250 depicted in FIG. 2C,display apparatus 270 includes a detector device 204 where the NIR lightsource 272 (e.g., light source 260 depicted in FIG. 2C) is separatedfrom the RGB light source 254. Distinctly, display apparatus 270 of FIG.2D includes a NIR light source 272 that is integrated into the detectordevice 204. The NIR light source 272 can be fabricated on the detectordevice 204, e.g., using epitaxial and/or lateral growth methods. Asdepicted in FIG. 2D, the NIR light source 272 can be fabricated embeddedin the a-Si/p-Si/other types of silicon material of the detectorintegrated circuit layer 226. Alternatively, the NIR light source 272can be fabricated and diced separately, and then integrated as a die tothe detector device 204 by bonding the die to the detector integratedcircuit layer 226 of the detector device 204.

In some implementations, the detector integrated circuit layer 226 isbetween the detector 222 and the display device 202 such that thereflected NIR light 125 enters the detector 222 through the detectorintegrated circuit layer 226. The NIR light source 272 and the detector222 are respectively at two opposite sides of the surface 231 of thesubstrate 227. In some implementations, the detector 222 is between thedetector integrated circuit layer 226 and the display device 202 suchthat the reflected NIR light 125 enters the detector 222 without passingthrough the detector integrated circuit layer 226. The NIR light source272 and the detector 222 are at the same side of the surface 231 of thesubstrate 227. In some implementations, the NIR light source 272 may beembedded in the substrate 227 at a position directly under the secondfilter region 266.

Subsequent to integrating the NIR light source 272 in the detectordevice 204, the detector device 204 and the display device 202 arebonded together, e.g., using wafer/die bonding techniques, at therespective interfaces 203 and 205, as described above with reference todetector device 204 and display device 202 in FIG. 1A.

FIG. 2E is a cross-sectional schematic of another example displayapparatus 280. The display apparatus 280 depicted in FIG. 2E is amonolithically integrated structure of the display apparatus 270described above with reference to FIG. 2D. Monolithic integration of thedisplay apparatus 280 includes a display device 202 and detector device204 that are fabricated using monolithic fabrication techniques, e.g.,epitaxial and/or lateral growth techniques, that does not involve amechanical bonding step to unify the display device 202 and the detectordevice 204 at the interface 242.

In some implementations, the NIR light source 282 can protrude into thedisplay integrated control layer 208 (e.g., the a-Si layer) of thedisplay device 202, where growth of the a-Si layer for the displayintegrated control layer 208 using monolithic integration techniques canbe, in part, a lateral growth of a-Si over the NIR light source 282.

In some implementations, the NIR light source 282 can be beneath thea-Si layer of the display device, where the NIR light source 282 isembedded within the detector device 204 and below the interface 242,such that the NIR light source 282 is not located within the displaydevice 202.

In some implementations, thermal budget constraints can determinefabrication processes available for fabricating the monolithicallyintegrated structure of display apparatus 180. For example, detector 222can be a Ge detector and has a thermal budget of 800° C., where anystructures of the display apparatus 280 that are fabricated after the Gedetector 222 are restricted to not exceed 800° C. In another example,NIR light source 282 can be an InGaAs/InP VCSEL and has a thermal budgetnot exceeding 600° C. after the NIR light source 282 is epitaxiallyand/or laterally grown on the a-Si layer of the detector integratedcircuit layer 226 of the detector device 204.

In some implementations, the display apparatus 280 can be fabricatedutilizing both a mechanical bonding technique and a monolithicintegrated technique. For example, the display device 202 and thedetector device 204 may each be monolithically integrated and thenmechanically bonded together at interface 242. In another example, thedetector device 204 can include a bonding step to integrate the NIRlight source 282 with the detector device 204, e.g., to bond the NIRlight source 282 to a portion of detector integrated circuit layer 226,and where other aspects of the display apparatus (e.g., the detectorintegrated circuit layer 226 and the display device 202) are fabricatedusing monolithic integrated techniques, e.g., epitaxial and/or lateralgrowth of a-Si/p-Si/other types of silicon surrounding and over the NIRlight source 282.

In some implementations, the detector integrated circuit layer 226 isbetween the detector 222 and the display device 202 such that thereflected NIR light 125 enters the detector 222 through the detectorintegrated circuit layer 226. The NIR light source 272 and the detector222 are respectively at two opposite sides of the surface 231 of thesubstrate 227. In some implementations, the detector 222 is between thedetector integrated circuit layer 226 and the display device 202 suchthat the reflected NIR light 125 enters the detector 222 without passingthrough the detector integrated circuit layer 226. The NIR light source272 and the detector 222 are at the same side of the surface 231 of thesubstrate 227. In some implementations, the NIR light source 272 may beembedded in the substrate 227 at a position directly under the secondfilter region 266.

Fabrication Techniques for Display Apparatus

The various aspects of the display apparatus 100 as depicted in FIG. 1Acan be fabricated, for example, using complementarymetal-oxide-semiconductor (CMOS) microfabrication techniques, e.g.,photolithography processes, etching processes, deposition processes, andthe like. In some embodiments, fabrication of the display apparatus 100can include epitaxial and/or lateral growth of one or more layers ofmaterial (e.g., Si, SiGe, or Ge).

The various layers described in the display apparatus 100 can be grownon silicon substrates using various vacuum techniques, e.g.,chemical-vapor deposition (CVD), metal-organic chemical vapor deposition(MOCVD), molecular beam epitaxy (MBE), atomic layer deposition (ALD), orthe like. In some implementations, the shielding layer 110 is apolymeric material that can be can be spin-coated or sputtered over thedisplay integrated circuit layer 108.

A germanium detector 122 can be formed embedded in the silicon substrate127, for example, using epitaxial growth such as CVD, MOCVD, MBE, ALD,or any suitable method. Alternate detector configurations are describedin further detail with reference to FIGS. 3 and 4 below.

Interconnects 129 and IC layer 130 can be fabricated on the displayapparatus 100 in contact with respective detector control circuits 128,using, for example a process including a deposition, lift-off, oretching step. Deposition can be performed using, for example, a metalevaporation.

Example Photodetector Devices and Operation

Detectors 122 and 222 described generally with reference to FIGS. 1A and2A can be Ge or SiGe detectors. In general, a Ge or SiGe detector can beused to absorb NIR photons and convert optical signal into electricalsignal. In some implementations, the detector (e.g., detector 122) canbe replaced by a single-output photodetector or dual-outputphotodetector, and can be used to perform time-of-flight detectionmeasurements when incorporated in the display apparatuses describedherein.

In time-of-flight (TOF) detection measurements, depth information of athree-dimensional object (e.g., object 121) may be determined using aphase difference between a transmitted light pulse and a detected lightpulse, e.g., a MR light pulse from NIR light source 114. For example, atwo-dimensional array of pixels may be used to reconstruct athree-dimensional image of a three-dimensional object, where each pixelmay include one or more photodetectors (e.g., detectors 122) forderiving depth information of the three-dimensional object. In someimplementations, time-of-flight applications use light sources havingwavelengths in the near-infrared (NIR) range. For example, alight-emitting-diode (LED) may have a wavelength of 850 nm, 940 nm, 1064nm, or 1310 nm, or 1550 nm. For TOF applications using NIR wavelengths,a multi-gate photodetector using germanium-silicon (GeSi) or a germanium(Ge) as the absorption material can be utilized.

FIG. 3 is a circuit diagram of an example single-output detector device300.

Absorption region 302, the p-doped region 304, and the first n-dopedregion 306 are supported by a first semiconductor layer 305, and thesecond n-doped region 312, the gate 314, and the floating-diffusioncapacitor 308 are supported by a second semiconductor layer 307. Thefirst semiconductor layer 305 and the second semiconductor layer 307 maybe semiconductor wafers, such as a silicon wafer used in standardintegrated circuit fabrication processes.

The p-doped region 304 is arranged on a first surface of the absorptionregion 302 facing away from a top surface of the first semiconductorlayer 305. The p-doped region 304 may repel the photo-electrons from thesurface of the absorption region 302 and may thereby increase the devicebandwidth. For example, the p-doped region 304 may have a p+ doping,where the dopant concentration is as high as a fabrication process mayachieve, e.g., about 5×10²⁰ cm⁻³, when the absorption region 302 isgermanium and doped with boron.

The n-doped region 306 is arranged on the first surface of theabsorption region 302 facing away from the top surface of the firstsemiconductor layer 305. The n-doped region 306 may be formed byimplantation of dopants into the absorption region 302.

The first semiconductor layer 305 may be separately processed from thesecond semiconductor layer 307. For example, the first semiconductorlayer 305 may be processed using a first fabrication process specializedfor forming absorption region 302, and the second semiconductor layer307 may be processed using a second fabrication process specialized forforming the gate 314. The second fabrication process may be, forexample, a sub 100 nm CMOS fabrication process for forming high-densitydigital circuits. A first portion of the interconnect 316 may befabricated during the processing of the first semiconductor layer 305,and a second portion of the interconnect 316 may be fabricated duringthe processing of the second semiconductor layer 307. The processedfirst and second semiconductor layers 305 and 307 may then be bonded ata bonding interface 318, mechanically coupling the first and secondsemiconductor layers 305 and 307, and electrically coupling theabsorption region 302 to the second n-doped region 312. The entity thatresults from bonding of the first and second layers 305 and 307 may bereferred to as a substrate.

The bonding of the first and semiconductor layers 305 and 307 mayoptically obscure the first surface of the absorption region 302 facingthe second semiconductor layer 307. As such, an optical signal 320 mayenter the absorption region 302 from a top surface of the firstsemiconductor layer 305 opposite to a bottom surface where theabsorption region 302 is formed.

The general operation of the detector device 300 is as follows.Photo-generated carriers such as electrons generated by the absorptionregion 302 may be repelled by the p-doped region 304 toward the firstn-doped region 306. Once the photo-generated carriers reach the firstn-doped region 304, additional force may be imparted on the carriers toinduce a flow of those carriers from the first n-doped region 306 to thefloating-diffusion capacitor 308 when the MOSFET 310 is turned on. Suchforce may be generated by engineering of the doping concentrations n1 ofthe first n-doped region 306, n2 of the second n-doped region 312, andn3 of the floating-diffusion capacitor 308. In general, a charge carrieris driven from a region of low doping concentration to a region of highdoping concentration, as the potential energy associated with a regionof lower doping concentration is higher than the potential energyassociated with a region of higher doping concentration. As such, bysetting the doping concentrations according to an inequality n3>n2>n1,the carriers stored at the first n-doped region 306 may be first driventoward the second n-doped region 312 having the second dopingconcentration n2 higher than the first doping concentration n1. Then,when the MOSFET 310 is turned on, the difference in doping concentrationn2 of the second n-doped region 312 and n3 of the floating-diffusioncapacitor 308 further drives the carriers toward the floating-diffusioncapacitor 308. As a result, the carrier transfer efficiency from theabsorption region 302 to the floating-diffusion capacitor 308 may beimproved.

FIG. 4 is a circuit diagram of an example dual-output detector 400. Thedetector 400 is a switched photodetector for converting an opticalsignal to an electrical signal. The detector 400 includes an absorptionlayer 402 fabricated on a substrate 404. The substrate 404 may be anysuitable substrate where semiconductor devices can be fabricated on. Forexample, the substrate 404 may be a silicon substrate. The absorptionlayer 402 includes a first switch 408 and a second switch 410.

In general, the absorption layer 402 receives an optical signal 412 andconverts the optical signal 412 into electrical signals. The absorptionlayer 402 may be intrinsic, p-type, or n-type. In some implementations,the absorption layer 402 may be formed from a p-type GeSi material. Insome implementations, the absorption layer 402 may be composed of Ge.The absorption layer 402 is selected to have a high absorptioncoefficient at the desired wavelength range. For NIR wavelengths, theabsorption layer 402 may be a GeSi mesa, where the GeSi absorbs photonsin the optical signal 412 and generates electron-hole pairs. Thematerial composition of germanium and silicon in the GeSi mesa may beselected for specific processes or applications.

In some implementations, the absorption layer 402 is designed to have athickness t. For example, for 850 nm or 940 nm wavelength, the thicknessof the GeSi mesa may be approximately 1 μm to have a substantial quantumefficiency. In some implementations, the absorption layer 402 includesgermanium and is designed to absorb photons having a wavelength between800 nm and 2000 nm, the thickness t of the absorption layer 402 isbetween 0.1 microns and 2.5 microns. In some embodiments, the thicknesst of the absorption layer 10 is between 0.5 microns and 5 microns forhigher quantum efficiency. In some implementations, the surface of theabsorption layer 402 is designed to have a specific shape. For example,the GeSi mesa may be circular, square, or rectangular depending on thespatial profile of the optical signal 412 on the surface of the GeSimesa. In some implementations, the absorption layer 402 is designed tohave a lateral dimension d for receiving the optical signal 412. Forexample, the GeSi mesa may have a circular or a rectangular shape, whered can range from 1 μm to 50 μm.

A first switch 408 and a second switch 410 have been fabricated in theabsorption layer 402. The first switch 408 is coupled to a first controlsignal 422 and a first readout circuit 424. The second switch 410 iscoupled to a second control signal 432 and a second readout circuit 434.In general, the first control signal 422 and the second control signal432 control whether the electrons or the holes generated by the absorbedphotons are collected by the first readout circuit 424 or the secondreadout circuit 434.

In some implementations, the first switch 408 and the second switch 410may be fabricated to collect electrons. In this case, the first switch408 includes a p-doped region 428 and an n-doped region 426. Forexample, the p-doped region 428 may have a p+ doping, where theactivated dopant concentration may be as high as a fabrication processmay achieve, e.g., the peak concentration may be about 5×10²⁰ cm⁻³ whenthe absorption layer 402 is germanium and doped with boron. In someimplementation, the doping concentration of the p-doped region 428 maybe lower than 5×10²⁰ cm⁻³ to ease the fabrication complexity at theexpense of an increased contact resistance. The n-doped region 426 mayhave an n+ doping, where the activated dopant concentration may be ashigh as a fabrication process may achieve, e.g., the peak concentrationmay be about 1×10²⁰ cm⁻³ when the absorption layer 402 is germanium anddoped with phosphorous. In some implementation, the doping concentrationof the n-doped region 426 may be lower than 1×10²⁰ cm⁻³ to ease thefabrication complexity at the expense of an increased contactresistance. The distance between the p-doped region 428 and the n-dopedregion 426 may be designed based on fabrication process design rules. Ingeneral, the closer the distance between the p-doped region 428 and then-doped region 426, the higher the switching efficiency of the generatedphoto-carriers. However, reducing of the distance between the p-dopedregion 428 and the n-doped region 426 may increase a dark currentassociated with a PN junction formed between the p-doped region 428 andthe n-doped region 426. As such, the distance may be set based on theperformance requirements of the switched photodetector 100. The secondswitch 410 includes a p-doped region 438 and an n-doped region 436. Thep-doped region 438 is similar to the p-doped region 428, and the n-dopedregion 436 is similar to the n-doped region 426.

In some implementations, the p-doped region 428 is coupled to the firstcontrol signal 422. For example, the p-doped region 428 may be coupledto a voltage source, where the first control signal 422 may be an ACvoltage signal from the voltage source. In some implementations, then-doped region 426 is coupled to the readout circuit 424. The readoutcircuit 424 may be in a three-transistor configuration consisting of areset gate, a source-follower, and a selection gate, a circuit includingfour or more transistors, or any suitable circuitry for processingcharges. In some implementations, the readout circuit 424 may befabricated on the substrate 404. In some other implementations, thereadout circuit 424 may be fabricated on another substrate andintegrated/co-packaged with the detector 400 via wafer/die bonding orchip stacking.

The p-doped region 438 is coupled to the second control signal 432. Forexample, the p-doped region 438 may be coupled to a voltage source,where the second control signal 432 may be an AC voltage signal havingan opposite phase from the first control signal 422. In someimplementations, the n-doped region 436 is coupled to the readoutcircuit 434. The readout circuit 434 may be similar to the readoutcircuit 424.

The first control signal 422 and the second control signal 432 are usedto control the collection of electrons generated by the absorbedphotons. For example, when voltages are used, if the first controlsignal 422 is biased against the second control signal 432, an electricfield is created between the p-doped region 428 and the p-doped region438, and free electrons drift towards the p-doped region 428 or thep-doped region 438 depending on the direction of the electric field. Insome implementations, the first control signal 422 may be fixed at avoltage value V_(i), and the second control signal 432 may alternatebetween voltage values V_(i)±ΔV. The direction of the bias valuedetermines the drift direction of the electrons. Accordingly, when oneswitch (e.g., the first switch 408) is switched “on” (i.e., theelectrons drift towards the p-doped region 428), the other switch (e.g.,the second switch 410) is switched “off” (i.e. the electrons are blockedfrom the p-doped region 438). In some implementations, the first controlsignal 422 and the second control signal 432 may be voltages that aredifferential to each other.

In general, a difference (before equilibrium) between the Fermi level ofa p-doped region and the Fermi level of an n-doped region creates anelectric field between the two regions. In the first switch 408, anelectric field is created between the p-doped region 428 and the n-dopedregion 426. Similarly, in the second switch 410, an electric field iscreated between the p-doped region 438 and the n-doped region 436. Whenthe first switch 408 is switched “on” and the second switch 410 isswitched “off”, the electrons drift toward the p-doped region 428, andthe electric field between the p-doped region 428 and the n-doped region426 further carries the electrons to the n-doped region 426. The readoutcircuit 424 may then be enabled to process the charges collected by then-doped region 426. On the other hand, when the second switch 410 isswitched “on” and the first switch 408 is switched “off”, the electronsdrift toward the p-doped region 438, and the electric field between thep-doped region 438 and the n-doped region 436 further carries theelectrons to the n-doped region 436. The readout circuit 434 may then beenabled to process the charges collected by the n-doped region 436.

In some implementations, a voltage may be applied between the p-dopedand the n-doped regions of a switch to operate the switch in anavalanche regime to increase the sensitivity of the switchedphotodetector 400. For example, in the case of an absorption layer 402including GeSi, when the distance between the p-doped region 428 and then-doped region 426 is about 100 nm, it is possible to apply a voltagethat is not greater than 7 V to create an avalanche gain between thep-doped region 428 and the n-doped region 426.

In some implementations, the substrate 404 may be coupled to an externalcontrol. For example, the substrate 404 may be coupled to an electricalground, or a preset voltage less than the voltages at the n-dopedregions 426 and 436. In some other implementations, the substrate 404may be floated and not coupled to any external control.

The detector 400 further includes a p-well region 440 and n-well regions442 and 444. In some implementations, the doping level of the n-wellregions 442 and 444 may range from 10¹⁶ cm⁻³ to 10²⁰ cm⁻³. The dopinglevel of the p-well region 440 may range from 10¹⁶ cm⁻³ to 10²⁰ cm⁻³.

In some implementation, the absorption layer 402 may not completelyabsorb the incoming photons in the optical signal 412. For example, ifthe GeSi mesa does not completely absorb the incoming photons in the NIRoptical signal 412, the NIR optical signal 412 may penetrate into thesilicon substrate 404, where the silicon substrate 404 may absorb thepenetrated photons and generate photo-carriers deeply in the substratethat are slow to recombine. These slow photo-carriers negatively affectthe operation speed of the switched photodetector. Moreover, thephoto-carries generated in the silicon substrate 404 may be collected bythe neighboring pixels, which may cause unwanted signal cross-talksbetween the pixels. Furthermore, the photo-carriers generated in thesilicon substrate 404 may cause charging of the substrate 404, which maycause reliability issues in the switched photodetector.

To further remove the slow photo-carriers, the detector 400 may includeconnections that short the n-well regions 442 and 444 with the p-wellregion 440. For example, the connections may be formed by a silicideprocess or a deposited metal pad that connects the n-well regions 442and 444 with the p-well region 440. The shorting between the n-wellregions 442 and 444 and the p-well region 440 allows the photo-carriersgenerated in the substrate 404 to be recombined at the shorted node, andtherefore improves the operation speed and/or reliability of theswitched photodetector. In some implementation, the p-well region 440 isused to passivate and/or minimize the electric field around theinterfacial defects between the absorptive layer 402 and the substrate404 in order to reduce the device dark current.

Though some embodiments of photodetectors are described with referenceto FIGS. 3 and 4 herein, other embodiments are possible. For example,additional suitable embodiments are described in US Patent Application2018/0247968 A1 published on Aug. 30, 2018, US Patent Application2018/0233521 A1 published on Aug. 16, 2018, the entire contents of whichare incorporated herein by reference.

Example Embodiment of a Liquid Crystal-Based Display Apparatus

In some embodiments, the display apparatus includes a liquid crystaldisplay (LCD). The display device can include a liquid crystal layerbetween a first electrode area and a second electrode area. The displayapparatus can further include a backlight module positioned under thedisplay device, and a first and a second polarizer film sandwiching theliquid crystal layer. A color filter can be located between the firstpolarizer and the second polarizer. A detector device can be locatedbetween the backlight module and the display device.

FIG. 5A is a schematic of an example liquid crystal-based displayapparatus 500, which includes a backlight module 502 emitting visiblelight 503, a rear polarizer 504 a and a front polarizer 504 b, and aglass substrate module 506. The glass substrate module 506 includes theliquid crystal layer 508, a TFT circuits layer 510, and a color filterlayer 512. The backlight module 502 includes a backlight source 514,e.g., LEDs or fluorescent lamp, a light guiding plate 516, and,optionally, a reflector 517.

Additionally, the display apparatus 500 includes a detector module 518,including multiple detectors 520 (e.g., detectors 122 as described inFIG. 1A) and multiple detector control circuits 522 (e.g., detectorcontrol circuits 128 in FIG. 1A). Detector module 518 also includes anNIR light source 524, e.g., an NIR laser diode, NIR OLEDs, MR MicroLEDS, or the like. Detector module 518, as described as the detectordevice 104 with reference to FIGS. 1A through 1E, can include a detectorintegrated circuit layer (e.g., detector integrated circuit layer 126)including an array of multiple detector control circuits 522 inelectrical contact with the multiple detectors 520.

In some implementations, as described with reference to detector device104 in FIG. 1C and detector device 204 in FIG. 2C, each NIR light source524 of the multiple NIR light sources is in electrical contact with atleast one laser control circuit 527. NIR light source 524 is a laserdiode, e.g., an NIR VCSEL that is separately fabricated, diced andbonded to the detector device and electrically connected to the detectormodule 518 via the one or more laser control circuits 527.

In some implementations, as described with reference to detector device104 in FIG. 1D and detector device 204 in FIG. 2D, the MR light source524 is a laser diode, e.g., a NIR VCSEL, that is monolithicallyfabricated on the detector module 518 and electrically connected to thedetector module 518 via the one or more laser control circuits 527.

In some implementations, as depicted by example liquid crystal-baseddisplay apparatus 501 in FIG. 5A, the detector module 518 is locatedbetween the backlight module 502 and the rear polarizer 504 a, where NIRlight 525 from the NIR light source 524 is directed substantially normalto a surface 526 of the display apparatus 500. Reflected NIR light 528that is reflected from an object 530 can be absorbed by a detector 520in the detector module 518.

In some implementations, as depicted in FIG. 5B, the detector module 518is located below the backlight module 502, where the NIR light 525 fromthe NIR light source 524 is directed substantially normal to a surface526 of the display apparatus 500.

A location of the detector module 518 and a location of the NIR lightsource 524 can be selected in part based on transmission properties ofthe composite layers of the display apparatus 500 to near-infraredwavelengths. Additionally, a particular range of wavelengths of NIRlight can be selected based in part on an attenuation factor of therange of wavelengths through the display apparatus. For example, 1.55microns wavelength can have a 25% attenuation factor from origination atthe NIR light source 524 until it reaches the top surface 526 of thedisplay apparatus. In another example, a range of wavelengths 750 nm-1.1microns may have an attenuation factor of 45% from an origination pointat the NIR light source 524 until it reaches the top surface 526 of thedisplay apparatus. In some implementations, longer wavelengths can havesmaller attenuation factors than shorter wavelengths in the materialsutilized for the display apparatus 500.

In some implementations, the detector module 518 can be separatelyfabricated and bonded in a post-processing step to the rest of thedisplay apparatus 500.

In some implementations, as described above with reference to FIGS. 3and 4, a detector 520 can be a Ge or SiGe detector, or can be asingle-output or dual-output photodetector configured to performtime-of-flight measurements.

Example Process for the Display Apparatus

In general, the NIR light source is located below a display device,e.g., display device 102 in FIG. 1A, such that the NIR light emitted bythe NIR light source is first deflected/scattered by one or more layersand/or features of the display device that are located between the NIRlight source and the object of interest. The non-deflected/scattered NIRlight then reflects off of the object and the reflected NIR light thatis incident on the detector device of the display apparatus can bemeasured by one or more detectors (e.g., detectors 122 in FIG. 1A) thatare part of the detector device (e.g., detector device 104) of thedisplay apparatus. Thus, a calibration process can be performed toremove a pattern that is generated by the MR light passing through theone or more layers of the display device prior to encountering theobject of interest. Software image reconstruction can be used to removethe background noise and/or resulting patterns and generate a calibratedimage of the object.

FIG. 6 is an example process 600 for a display apparatus (e.g., displayapparatus 100 in FIG. 1A) to detect the proximity of objects (e.g., afinger, a hand, or a face) to a surface of the display apparatus.

A calibration or “dark” image can be measured by first determining thatthere are no object(s) within a threshold distance (e.g., a fewmillimeters, tens of centimeters, a few hundred centimeters) of asurface of the display apparatus (602). In order to take a calibrationimage, objects of interest (e.g., object 121) should not be within athreshold distance (e.g., distance 132 in FIG. 1A) of a surface of thedisplay device (e.g., the front surface 123 of display device 102 inFIG. 1A). In some implementations, a threshold distance can be a fewmillimeters for a finger, tens of centimeters for a hand, tens to a fewhundred centimeters for a face. Objects that are outside a thresholddistance can be objects that are too far from the surface of the displaydevice for a minimum electrical signal that is measured at the detectorfrom reflected NIR light that reaches the detector (e.g., detector 122)of the display apparatus. A minimum electrical signal can depend, inpart, on a sensitivity of the particular detector. For example, aminimum electrical signal can be, for example, at least >1 μV ofelectrical signal. At a distance greater than the threshold distance,the object can be disregarded.

In some implementations, the calibration image data can be collectedduring a set up process for the display apparatus, e.g., in a factorysetting or when a user initializes the display apparatus. A calibrationimage can be measured, for example, in a dark room or an environmentisolated from stray NIR light.

Near-infrared light is emitted from the near-infrared light source(604). NIR light (e.g., NIR light 124, MR light 164, etc.) is emittedfrom the near-infrared light source. NIR light source can be, forexample, an NIR OLED, an NIR MicroLED, an NIR laser diode, or anothersource of NIR light. The display apparatus can include an array ofmultiple NIR light sources, each emitting a NIR light and where each NIRlight source is electrical connected to a control device, e.g., adisplay control circuit 116 or a laser control device 168. The emittedNIR light can range, for example, between 750 nm-1.65 microns. Inanother example, the emitted light can be 1.55 microns. The NIR lightsource can emit NIR light having a power ranging between 1 mW to a fewWatts.

NIR light can be reflected (e.g., refracted or deflected) off of one ormore intermittent layers between the emitting NIR light source and afront surface 123 of the display device 102. In some implementations,for example in the display apparatus 100 of FIG. 1A, the MR light isreflected off of the transparent conductive oxide layer (e.g., firstelectrode area), and a transparent layer 106. In some implementations,for example in the display apparatus 170 of FIG. 1D, the NIR light isreflected off of one or more of the layers of the display device 102,e.g., the display integrated control layer, first electrode area,shielding layer, or the second electrode area).

Baseline image data is collected, where the baseline image data includesmeasured reflected MR light from the MR light source that is reflected,e.g., scattered, deflected, etc., from the one or more layers of thedisplay apparatus (606). Baseline image data is collected at eachdetector of the multiple detectors of the display apparatus. Image datacan be electrical signal generated from optical signal, where theoptical signal is the reflected NIR light absorbed by each detector.

In some implementations, image data can be time-of-flight measurementsmade at each detector or photodetector of the multipledetectors/photodetectors of the display apparatus, where thetime-of-flight measurement corresponds to phase, time, frequency, etc.,delay of the optical signal (e.g., the emitted NIR light from the MRlight source) to reach a particular detector via a reflection (e.g.,reflection off of a layer of the display device).

Each detector of the multiple detectors has a known position relative toeach other detector, e.g., in an array of detectors across a surface ofthe display apparatus. The baseline image data can include a respectivemeasurement (e.g., electrical signal, time-of-flight measurement, etc.)from each detector and metadata including a location of the particulardetector relative to the array of detectors.

Once baseline image data has been collected, operation of the displayapparatus can proceed. Near-infrared light is emitted from thenear-infrared light source (608).

Reflected image data is collected, where the reflected image dataincludes measured reflected MR light from the MR light source that isreflected from the object within the threshold distance (610). Asdiscussed above with reference to step 704, NIR light (e.g., NIR light124, MR light 164, etc.) is emitted from the near-infrared light source.The emitted NIR light can imping on an object that is within a thresholddistance of a top surface (e.g., the front surface 123) of the displayapparatus and reflect off of the object. The reflected NIR light (e.g.,reflected NIR light 125) can be incident on the display apparatus suchthat at least a portion of the reflected NIR light is incident on one ormore of the detectors in the detector device and is absorbed by the oneor more detectors.

Reflected image data is collected at each detector of the multipledetectors of the display apparatus. Reflected image data can beelectrical signal generated from optical signal, where the opticalsignal is the reflected NIR light absorbed by each detector.

In some implementations, reflected image data can be time-of-flightmeasurements made at each detector or photodetector of the multipledetectors/photodetectors of the display apparatus, where thetime-of-flight measurement corresponds to phase, time, frequency, etc.,delay of the optical signal (e.g., the emitted NIR light from the MRlight source) to reach a particular detector via a reflection (e.g.,reflection off of the object that is within a threshold distance of thedisplay device).

Each detector of the multiple detectors has a known position relative toeach other detector, e.g., in an array of detectors across a surface ofthe display apparatus. The reflected image data can include a respectivemeasurement (e.g., electrical signal, time-of-flight measurement, etc.)from each detector and metadata including a location of the particulardetector relative to the array of detectors.

A calibrated image is determined of the object using the baseline imagedata and the reflected image data (612). In some implementations, acalibrated image can be generated based in part on a subtraction of thebaseline image data from the reflected image data for each of thedetectors across the multiple detectors. Image processing techniques canbe implemented to construct an image of the object within the thresholddistance of the display apparatus from the individual measurements ateach of the multiple detectors in the array of detectors.

The calibrated image is provided of the object (614). In someimplementations, the calibrated image of the object is provided asfeedback to an application running on the display apparatus (e.g., agraphical user interface for a mobile device). In some implementations,the calibrated image is provided to motion, facial, gesture, andenvironmental tracking software, e.g., on a user tablet, mobile phone,television screen, or LCD panel.

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of anyfeatures or of what may be claimed, but rather as descriptions offeatures specific to particular embodiments. Certain features that aredescribed in this specification in the context of separate embodimentscan also be implemented in combination in a single embodiment.Conversely, various features that are described in the context of asingle embodiment can also be implemented in multiple embodimentsseparately or in any suitable subcombination. Moreover, althoughfeatures may be described above as acting in certain combinations andeven initially claimed as such, one or more features from a claimedcombination can in some cases be excised from the combination, and theclaimed combination may be directed to a subcombination or variation ofa subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingmay be advantageous. Moreover, the separation of various systemcomponents in the embodiments described above should not be understoodas requiring such separation in all embodiments, and it should beunderstood that the described program components and systems cangenerally be integrated together in a single software product orpackaged into multiple software products.

Thus, particular embodiments of the subject matter have been described.Other embodiments are within the scope of the following claims. In somecases, the actions recited in the claims can be performed in a differentorder and still achieve desirable results. In addition, the processesdepicted in the accompanying figures do not necessarily require theparticular order shown, or sequential order, to achieve desirableresults. In certain implementations, multitasking and parallelprocessing may be advantageous.

What is claimed is:
 1. A display apparatus comprising: a display devicehaving a plurality of pixels, a front side, and a back side opposite thefront side, the display device comprising: a transparent layer; anddisplay control circuitry configured to control the plurality of pixels;a light source configured to emit an optical signal having a wavelengthhigher than 800 nm towards the front side of the display device; afilter configured to pass light having at least the wavelength of theoptical signal; and a detector device located at the back side of thedisplay device, the detector device comprising: one or morephotodetectors comprising: a substrate formed based on a first material;and one or more detection regions formed on the substrate, wherein theone or more detection regions are formed based on a second materialdifferent from the first material, and wherein the one or more detectionregions are positioned to receive a portion of the optical signalpropagating from the front side of the display device to the back sideof the display device along a path; and a detector integrated circuitlayer comprising one or more detector control circuits electricallycoupled to the one or more photodetectors, wherein the one or morephotodetectors are positioned such that the portion of the opticalsignal propagating from the front side of the display device to the backside of the display device passes through the substrate formed based onthe first material before entering the one or more detection regions ofthe one or more photodetectors.
 2. The display apparatus of claim 1,wherein the first material comprises silicon.
 3. The display apparatusof claim 1, wherein the second material comprises germanium orgermanium-silicon.
 4. The display apparatus of claim 1, wherein thelight source is electrically coupled to the display control circuitry.5. The display apparatus of claim 1, wherein the light source iselectrically coupled to the detector integrated circuit layer.
 6. Thedisplay apparatus of claim 1, wherein the display control circuitrycomprises TFTs, CMOS transistors, or a combination thereof.
 7. Thedisplay apparatus of claim 1, wherein the one or more detector controlcircuits comprise TFTs, CMOS transistors, or a combination thereof. 8.The display apparatus of claim 1, wherein display device furthercomprises an array of visible organic light-emitting diodes, visiblemicro-light emitting diodes, or a combination thereof.
 9. The displayapparatus of claim 1, wherein the light source comprises an array of NIRorganic light-emitting diodes, NIR micro-light emitting diodes, or acombination thereof.
 10. The display apparatus of claim 1, wherein thelight source is integrated with the display device.
 11. The displayapparatus of claim 1, wherein the light source is integrated with thedetector device.
 12. The display apparatus of claim 1, wherein thedetector integrated circuit layer is formed based on the first material.13. The display apparatus of claim 12, further comprising a growth or abonding interface between the display device and the detector device.14. The display apparatus of claim 13, wherein the one or morephotodetectors and the detector integrated circuit layer are bonded toform a chip stack having the one or more detection regions arrangedbetween the substrate of the one or more photodetectors and the detectorintegrated circuit layer.
 15. The display apparatus of claim 1, whereinthe detector device is configured to provide an output representingproximity information or time-of-flight information associated with anobject.
 16. A method for operating a display apparatus, the methodcomprising: emitting, by a light source, an optical signal having awavelength higher than 800 nm towards a transparent layer of a displaydevice; receiving, by the transparent layer of the display device, areflected optical signal from an object; receiving, by a filterconfigured to pass light having at least the wavelength of the opticalsignal, a first portion of the reflected optical signal that is weakerthan or equal to the reflected optical signal; receiving, by a substrateof a photodetector located at a back side of the display device, asecond portion of the reflected optical signal that is weaker than orequal to the first portion of the reflected optical signal, wherein thesubstrate is formed based on a first material; receiving, by one or moredetector regions of the photodetector, a third portion of the reflectedoptical signal that is weaker than or equal to the second portion of thereflected optical signal, wherein the one or more detector regions areformed based on a second material different from the first material;generating, by a detector integrated circuit layer comprising one ormore detector control circuits electrically coupled to thephotodetector, an electrical signal representing the third portion ofthe reflected optical signal received by the one or more detectorregions; and determining, based on the electrical signal and by one ormore circuitry, data representing proximity information ortime-of-flight information associated with the object.
 17. The method ofclaim 16, wherein determining the data further comprises determining acalibrated image based on a baseline image.
 18. The method of claim 17,further comprising determining the baseline image, wherein determiningthe baseline image comprises: emitting, by the light source, an opticalsignal in an environment having no object within a threshold distance;and determining the baseline image based on an electrical signalgenerated by the detector integrated circuit layer in the environment.19. The method of claim 17, further comprising providing the calibratedimage as feedback to an application running on the display apparatus.20. The method of claim 16, wherein the first material comprisessilicon, and wherein the second material comprises germanium orgermanium-silicon.